This research will study (identify and enumerate) diatoms in the Sirius Formation and age- equivalent and related sediments collected on various parts of Antarctica with the following objectives in mind: 1. A relatively high resolution stratigraphy will place age constraints upon each sample. These data will allow such topics as the timing of late Neogene deglaciation and reglaciation of Antarctica, glacial overriding events and the deposition of non- ice related sediments. 2. The diatoms found in the tills and other Neogene sediment from the Antarctic continent impose some constraints on our paleoenvironmental interpretation of this region and the surrounding Southern Ocean. Because many of the species found in these sediments are extant, diatoms can be used to characterize the paleotemperature and paleoclimate regime around the continent, particularly for the middle to late Pliocene. Since this time interval covers the prelude to, and inception of, northern hemisphere glaciation, these data will draw Antarctica into the discussion of events leading up to the Quaternary climatic deterioration.